Method for retaining the radioactivity of liquids intended for injections



July 1, 1 7- s. KLINGHOFFER METHOD FDR RETAINING THE RADIOACTIVII'Y 0F LIQUIDS INTENDED FOR INJECTIONS Flled Jan 13, 1939 Patented July 1, 1947 TJECTIONS TIVITY OFWLIQUID S: INT ENDEDYEFOR- IN- Stfan Kliiighhfler, Parisi Erancej -vested iiiithe Attorney General? of the United States Application January 13, 1935?; Serial N6'."2"50,7 46 In France January 15, 1938 2 Claims.

The present invention relates to a process for retaining and keeping constant the radioactivity of any liquid intended for injections.

It is known that for the treatment of certain diseases by means of injections of liquids containing radioactive material, it has already been proposed to replace the liquid containing radioactive substances by liquids containing gaseous radioactive elements, 1. e. radon, thoron and actinon being isotopes of the same element usually called radon. In order to make efiicacious the treatment given by means of these latter liquids, it is necessary that the degree of radioactivity of the liquids used be accurately measured. It is therefore indispensable for the liquids containing radioactive material to be used a fixed and relatively short lapse of time after they have been prepared.

The present invention has for its object a process which makes it possible to prepare such liquids in the laboratory, and to retain a constant degree of radioactivity in same for a practically indefinite time, thereby enabling them to be stocked by all chemists. The degree of radioactivity of a liquid is constant when it produces a constant number of radioactive alpha and beta rays and a constant amount of gamma rays in a unit of time.

The process according to the invention is essentially characterized by the fact that it consists in immersing in the liquid in which a constant degree of radioactivity is to be maintained, a device which contains a predetermined quantity of substance capable of producing radon, said quantity being so dosed as to maintain the liquid, which has previously been rendered radioactive, in radioactive equilibrium. The liquid preferably has previously been rendered radioactive as to contain a predetermined amount of radon. When the liquid is maintained in radioactive equilibrium, the disintegrating radon atoms ar displaced, atom by atom, by new radon atoms, produced by the radioactive substance contained in the device above referred to.

Other advantages and features of the invention will become apparent from the ensuing description taken with reference to the accompanying drawing in which Figs, 1 and 2 show sectional elevations of two embodiments of an ampoule by means of which the process according to the invention may be carried out.

According to the embodiment shown in Fig. 1, I designates an ampoule of any known type of the kind of those commonly used for medical purposes and provided, in the known manner, with 2 two tapered points 2 and 3. Ampoule I may for example consist of glass to facilitate sealing thereof.

The degree of radioactivity of any liquid which 5 is contained in said ampoule and is intended for treatments by means of injection, is kept constant by fixing on the inner wall of the ampoule before filling and closing same a thread 4 made of a material which is capable of producing radon or radon and its isotopes. A material which will produce radon and its isotopes may consist of or contain radium, thorium, and actinium and compounds thereof. Radium sulphate or radiumbarium-sulphate may advantageously be used for this purpose.

The thread 4 is held in position by means of a coating of paraflin, for example.

Instead of being formed in the shape which has just been mentioned, the material capable of producing radon might be formed in the shape of a stick 8 fixed on one of the points 1 of the ampoule 5. As shown, the ampoule 5 is provided in the usual manner with a tapered point 6.

The volume of the thread 4 or that of the stick 8 is so calculated that the quantity of radon produced by the material which forms them keeps the liquids contained in the ampoules I or 5 in radioactive equilibrium.

The radioactive material of which thread 4 or 80 stick a is formed should be insoluble in the liquid contained in the ampoule. Otherwise, the radium thorium or actinium might dissolve in the liquid and might have a harmful efiect which is due to the fact that radon and its isotopes produces only alpha rays, while their mother substances and their disintegration products also produce beta and gamma rays which have a different biological action.

The liquid contained in ampoule I may be a physiological salt solution containing NaCl. This liquid together with the radon contained therein is injected for instance into the blood by means of a hypodermic syringe. The radon will disintegrate after a few days and thus the medicinal treatment can be exactly controlled due to the predetermined constant degree of radioactivity of the liquid to be injected.

It is obvious that the invention is in nowise limited to the embodiments which have been more especially described by way of example, but that it extends to all possible modifications coming, fairly, within the scope of the appended claims.

I claim: 1. In a closed ampoule of the type having at least one tapered point and containing a radioactivated injection liquid, an insoluble body of radon producing substance secured within the interior of the ampoule in contact with the liquid for activating the liquid, said body being proportioned in size and radon producing capacity to substantially permanently maintain the radon activity of the injection fluid constant.

2. In a closed ampoule containing radioactivated injection liquid, an insoluble stick of radon producing substance fixed within the ampoule in 10 contact with the liquid so as to activate the liquid, the size and radon producing capacity of said stick being proportioned to substantially permanently maintain the injection liquid in radio active equilibrium.

STEFAN KLINGHOFFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,626,338 Heublein Apr. 26, 1927 2,206,634 Fermi et a1 July 2, 1940 FOREIGN PATENTS Number Country Date 112,865 Great Britain J an. 31, 1918 36,796 Austria Mar. 26, 1909 15,139

Great Britain July 1, 1913 

